Many pet owners live under circumstances which require them to train their pets so that their pets perform their excretory functions in containers holding animal litter. Such circumstances include lack of available outdoor space in which the pets can perform their excretory functions, and even where such space is available, the pet owner's schedule may not afford the time to accompany the pet to such sites. Due to urbanization and the pace of modern life, these circumstances are becoming increasingly common. Thus, animal litter containers are becoming popular accessories for owners of not only cats, but also dogs, rabbits, and other animals.
The common animal litter container is generally some form of receptacle, usually box-like, which is designed to contain either non-clumping-type or clumping-type animal litter. The former type of litter is generally comprised of fibrous or granular particles which absorb moisture, and which may be treated with odor-absorbing chemicals and other additives to increase its life span, i.e., the length of time that the animal and pet owner can tolerate its use and presence. The life span of the litter can be increased by removing the animal waste from the litter, as by sifting the animal feces from the smaller litter particles. It may also be possible to sift urine-contaminated litter particles from unsoiled litter as well, since litter particles can swell when they absorb urine, and thus may be sifted out of the unsoiled litter due to their larger size. Clumping-type litter is similar to the non-clumping litter, but its particles bind to moisture and tend to agglomerate when they contact animal urine or feces. This litter has the advantage that soiled litter is more easily sorted from nonsoiled litter by a process of sifting the clump-like soiled litter agglomerations from the sand-like unsoiled litter. Because this process greatly increases the life span of the litter, the clumping-type litter is becoming increasingly popular. However, one drawback of this type of litter is that its dust, when inhaled, will adhere to mucous membranes in the lungs and sinuses. Therefore, excess agitation and other dust-creating manipulation of the litter should be avoided.
The prior art contains several examples of containers for animal litter and waste which include apparatus for cleaning animal waste from the container while retaining reusable animal litter. These containers generally use a mesh sifting operation to strain the animal wastes from fouled litter, leaving reusable litter behind. The containers are generally of two types. The first type are those that contain cleaning means whereby the container is cleaned by a complex cleaning mechanism. Examples are illustrated in U.S. Pat. No. 5,259,340 to Arbogast; U.S. Pat. No. 5,272,999 to Nussle; and U.S. Pat. No. 4,970,987 to Deyle. The second type of containers are those that utilize nonmechanical cleaning means. The container apparatus has no attached parts that move in relation to one another, i.e. the pet owner manipulates the fouled litter through the straining screen using a lifting, inverting, or other agitating operation. Examples are U.S. Pat. No. 5,168,834 to Buschur; U.S. Pat. No. 3,809,013 to Rigney et al.; and U.S. Pat. No. 5,211,133 to Foley The latter type of container has the advantage that it is generally easier to manufacture, easier to clean due to its simplicity, and more durable because it has no mechanism that will be fouled or corroded/degraded by animal wastes or used litter. However, despite these advantages, these latter containers still tend to have fouling of multiple components with animal wastes. The pet owner must generally be content to have animal waste residue remaining on one or more parts after a cleaning operation is completed, else he must manually rinse and scrub the residue from the container. Such manual cleaning is not only aesthetically unpleasant due to the smell and appearance of animal wastes, but also dangerous, since animal wastes can carry disease. As an example, feline wastes can harbor the microorganism that causes toxoplasmosis, and thus can be dangerous for pregnant and immunoimpaired persons to handle.
The prior art also contains apparatus which successfully avoid the need to clean residual waste from container components. U.S. Pat. No. 3,809,013 to bypasses the need for residual waste cleanup by simply making the cleaning apparatus, a sifting screen for separating waste from litter, disposable. However, a disposable screen entails the expense of replacement screens, and therefore it is desirable to have an animal litter container and cleaning apparatus that uses durable components meant for permanent use.
Other prior art devices disclose container and sifter designs which have lesser component fouling and cleaning problems than others.
U.S. Pat. No. 5,211,133 to Foley discloses a container comprised of a sifter which is placed within a receptacle and filled with litter. When the receptacle is to be cleaned of animal wastes, the sifter is lifted from the receptacle, causing the litter to fall from the sifter's mesh-like bottom into the receptacle. Animal waste is retained within the sifter. The disadvantage of the invention is that the planar sidewalls of the sifter are especially subject to fouling by animal wastes, and the invention also uses a relatively large number of components, thus increasing its manufacturing cost. A complete cleaning of the sifter would involve scrubbing or another aesthetically unpleasant manual form of cleaning. In addition, the sifter unit is inconvenient to replace within the receptacle after it is emptied of animal waste. After the sifter is lifted from the receptacle, the receptacle is left filled with litter, so the pet owner must either (1) empty the receptacle of litter, replace the sifter, and then refill the receptacle--a messy and time-consuming chore; or (2) try to push the sifter through the litter until it fully rests within the receptacle. This is a difficult task because the sifter's mesh bottom must be forced through the litter.
U.S. Pat. No. 5,168,834 to Buschur has similar disadvantages. This device has two receptacles, each having a rim bounding an inner cavity wherein litter may be placed. One receptacle is meant to be used as the animal litter container while the other is to be set aside for later use. When the used receptacle is to be cleaned, a screen-like sifter is clamped atop the rim of the used receptacle, the fresh receptacle is placed atop the sifter so that the two receptacles face each other with their cavities and rims adjacent but separated by the sifter, and the entire apparatus is inverted. Thus, the litter falls through the sifter from the used receptacle into the fresh receptacle, and the animal waste is left to rest on the sifter with the used receptacle resting above it. The sifter and the used receptacle are then unclamped from the fresh receptacle, which is now filled with litter, and the sifter and used receptacle are reinverted so that the used receptacle holds only the animal waste. The sifter is then unclamped from the used receptacle so that it may be emptied of animal waste. The disadvantage of Buschur's container is that inversion of the container will often fail to separate waste from litter. Instead, the container must be inverted, and then shaken so that all of the unused litter may be recovered. Furthermore, unless the receptacles are provided with some kind of liner, the used receptacle will be fouled with animal waste upon reinversion of the sifter and the used receptacle. In addition, the sifter itself contains several planar surfaces which are subject to fouling with animal waste, thereby requiring that the sifter itself be cleaned after each use.